Thermostatic switch



May 15, 1928.

F. F. FORSHEE THERMosTATIc SWITCH Filed May 20. 1926 V ATTORNEY PatentedMay 15, 1928.

UNITED STATES PATENT OFFICE.

.FRANK F. FORSHEE, 0F MANSFIELD, OHIO, ASSIGNOR T0 WESTINGHO'UBEELECTRIC & MANUFACTURING COMPANY, A CORPORATION OF PENNSYLVANIA.

THERMOSTATIC SWITCH.

Application 1ed May 20,

My invention relates to thermostatic switches and more particularly tothermostat-ic switches used-to control the temperature of sad irons andother electrically heated devices.

An object of my invention is to provide a simple, ecient thermostaticswitch which shall have relatively few parts and may be readilymanufactured at a low cost.

Another object of my invention is to provide simple means in such adevice to produce a substantial separation between relatively movablecontacts with only a slight deflection of the thermostat.,

Another object of my invention is to rovide, in a device of theabove-indicated character, a lever havin a member secured theretoorbridging a p urality of contacts, which lever has a loose, pivotalconnection with its support, thus insuring an emcient electricalconnection between the contacts in the bridging member under allconditions of operation, even though the bridging member has beendeformed on account or arcing or otherwise.

Another object of my invention is to provide simple, ecient means tohold the thermostatic disc in its proper operative position.,

Another object of my invention is to provide a simple means forconnecting the thermostat with the member supporting the movablecontact.

ther objects will be apparent from the disclosure,

rilhe present embodiment of my invention comprises a supporting platehaving lugs to hold a thermostat in spaced relation to the plate. A pairor contact members, each having an electrical connection to a terminalmember, are mounted on the plat-e. These contact members are normallyelectrically connected through a bridging Contact member mounted on alever which is loosely pivoted to the supporting plate. n. stud, that issecured to the thermostat and that passes through a hole in thesupporting plate, has means thereon to loosely engage the lever tooperatively connect the `lever with the thermostat.,

lln the drawing,

Fig., l is a top plan view of a thermostatic switch embodying myinvention.

192e. serai no. 116,359.

Figi 2 is a side elevational view of the switc shown in Fig., l; andFig.. 3 is a sectional view, taken on the line III-III of Fig. 1.

Referring to the drawing, a metallic supporting plate 10 which may, ofcourse, be of an desired shape, (but is here shown as circu ar) hasintegral lu s 1l extending substantially at right ang es thereto. Eachof the lugs ll is provided with a shoulder 12 which serves to maintain abimetallic thermostatic disc 13 in spaced relation to the plate. Toretain the thermostatic disc in that position, any suitable means may beused, but, in the present instance are deformed so as to produce slightprojections which bear against the bottom of the disc.

An opening lll, herein shown as elongated, is provided in the plate andreceives one arm l5 ci an lle-shaped lever 16, the other arm of whichnormally is substantially parallel to the plate, as best shown in Fi 3.The portion ot the arm l5, that exten s through the opening la ispreferably reduced in width to provide shoulders 17' to limit the extentto which the arm l5 will extend through the opening. The area oic theopening la is somewhat larger than the crosssectional area of thereduced portion of the arm l5, thus providing a loosely pivotedconnectionn rEhe arm l5 may be bent, as at i8 to retain it in theopening.,

idear the other end ore the lever is provided a bridging contact member19 that may be secured in place by any desired means, such as a rivet20. llhe bridging member and the rivet may be insulated from theremaining structure by an desired means, such as mica sheets 2i, l` isbridging member normally rests against, and electrically connects, twocontact members 22, each contact member resting on a -dat conductor 23.Each conductor is connected, at its opposite end, with a terminal post24'; which is provided a screw 25 for the purpose of securing aconductor 'to the post., The contact members 22 and the conducting bars23 may be insulated from the plate by means of mica sheets 26 and aresecured to the plate by suitable means, such as rivets 27,

A stud 28 is secured to the thermostatic disc, preferably at its center,by means of the lugs f any suitable securing means, vsuch 'as,nuts 29.The stud 28 extends through an openmsecuring means, -may be provided tomain-f .ing in the'supporting plate 10. This stud passes through' anopening 31 provided in the lever 16. The openings 30 and 31 are madesomewhat larger than the stud 28. y

Means are provided on the under side of the lever and mounted on thestud for, operatively engaging the leverupon operation of thethermostat. A convenient form of such meansis herein shown as a nut 32,

which is locked in .position by a nut 33.' Onv the upper side of thelever, a nut 34, or other bridging contact member 19, the oppositeContact member 22 and the corresponding conductor 23 to the terminalpost 24.

When the temperature of the surrounding medium rises above a certainpoint, the thermostat will operate to raise the stud 28 which, in turn,will raise the lever 16 by means of the nut 32. Since the lever ispivotally connected to the supporting plate at 14, only the outer end,which bears the contact bridging member, will be raised. This, ofcourse, breaks the electrical connection between the two contact members22.

Since the lever is loosely pivoted to the supporting plate 14 and sincethe nuts 32 and 34 do not'closely engage the lever 16, it is obviousthat the bridging contact member 19 will, at all times, engage thecontact 22 when the device is in horizontal position, as shown in thedrawing. If the lever were not loosely pivoted to the supporting plate,as in my invention, and the breaking contact member 19 were deformed, onaccount of arcing or from any other cause, the bridging contact membermight only engage one contact so that no current would flow. p

While I have herein illustrated and described a preferred form of myinvention, it is obvious that the inyention may. be otherwise utilizedand, therefore, I do not wish to be limited to such specific form orotherwise except. as defined by the appended claims.

I claim as my invention:

1. A thermally actuable switch comprising a supporting plate having anopening a thermostat supported by said plate, a lever of Lsliape,'onearm of said lever being normally parallel to said plate and having aninsulated bridging contact member on its outer end, the other arm havingits end portion loosely and pivotally fitting in Said opening, alost-motion connection between said thermostat and said lever andpositionedintermediate said opening and said bridging contact member,and a pair of insulated contact members on said plate and normallyelectrically connected through said bridging contact member.

2. A. thermally actuable switch comprisinga supporting plate having anopening, a thermostat supported by said plate, a lever of L-shape, onearm of said lever being normally parallel to said plate and having aninsulated bridging contact memberthereon, the other arm havingits endportion loosely and pivotally fitting in said opening, said lever beingoperatively connected with sald thermostat, and a pair of insulatedcontact members on said plate and normally electrically connected bysaid bridging contact member. V

In testimony whereof, l have hereunto `subscribed my name this 17th dayof May,

raamt F. Fonsi-IEE.

